Overcoming Jet Lag: What We Know from the Research

We know from the research that recovery from jet lag can take 5 to 14 days, particularly if you are traveling to the east. Long-distance travel puts your internal day-night cycle (circadian rhythms) out of sync with the time zone of your destination.

The research reveals a great deal about the dynamics of sleep chemistry and jet lag. These studies also provide a glimpse of the critical role of tryptophan in the body's systems that initiate sleep.

. The serotonin pathway - tryptophan is the nutrient from which the brain makes serotonin, which induces sleep by relaxing the body.

. Melatonin hormones - tryptophan is also the raw material from which melatonin is produced - this is a natural hormone that signals sleep in response to the decrease in light as the sun sets.

. Serotonin appears to be key in maintaining sleep patterns

Researchers at the University Hospital of Freiburg in Germany studied the effects of tryptophan depletion on the metabolism of serotonin in the brain. "Because serotonin is involved in sleep regulation and the regulation of [mood] on sleep, we studied the acute effects of tryptophan depletion and expected to induce similar changes in sleep patterns similar to those observed in depressed patients." Tryptophan depletion was found to have significant effects on sleep including an increased percentage of time awake and changes in sleep patterns.

U Voderholzer and others. "Impact of experimentally induced serotonin deficiency by tryptophan depletion on sleep EEG in healthy subjects." Neuropsychopharmacology. February 1998; Vol 18, No 2: pages 112-124

. Melatonin is the cue that initiates sleep

A French review of the research describes the role of melatonin in setting the body's internal clock. Melatonin is a hormone synthesized from tryptophan. "The circadian rhythm of melatonin is the same in man and all the laboratory animals studied, with [night-time] concentrations 3 to 10 times greater than during the daytime.Light is the major regulating factor which is cued by changes in light perceived by the retina, signaled to the hypothalamus." At twilight, as the sunlight fades, the decreasing light triggers the release of melatonin. This signal is the cue that initiates the process of falling asleep.

Y Touitou and others. "Melatonin and biological rhythms: various aspects in human physiopathology. Annales Pharmaceutiques Francaises. 1996; Vol 54, No 6: pages 241-250.

. Tryptophan supports both serotonin and melatonin levels

The Department of Psychiatry at Fort Sam Houston in Texas studied the role of tryptophan. In their review of the literature, they confirmed that, "tryptophan is a precursor of serotonin and melatonin."

ME Levine and LK Duffy. "Seasonal variation of the amino acid, L-tryptophan, in interior Alaska . International Journal of Circumpolar Health . 1998; Vol. 57, Suppl. 1: pages 386-388.

. Depleting tryptophan lowers serotonin and melatonin

At the Connecticut Mental Health Center in New Haven a study was conducted to determine the effects of serotonin function on night-time melatonin secretion. Healthy volunteers underwent tryptophan depletion, which decreased tryptophan to less that 20% of initial levels. Blood samples were obtained before and after the depletion and tested for melatonin and tryptophan. Researchers reported, "Melatonin secretion was decreased in all eight subjects after tryptophan depletion. These results suggest that reduced tryptophan levels.in the bloodstream and presumably brain serotonin concentrations decrease nocturnal melatonin secretion in humans."

RC Zimmernamm and others. "Effects of acute tryptophan depletion on nocturnal melatonin secretion in humans." The Journal of Clinical Endocrinology and Metabolism. May 1993; Vol 76, No 5: pages 1160-1164.

. Supplementing with tryptophan improves sleep

A clinical trial at the University of Manitoba in Canada measured the effects of L-tryptophan on objective and subjective measures of sleepiness and examined their relationship to blood L-tryptophan levels. There was a highly significant correlation between blood L-tryptophan and sleep delay. When tryptophan levels were raised, problems with delayed sleep resolved. "We conclude the L-tryptophan reduced delays in sleep in healthy patients and that this correlates with tryptophan blood levels."

CF George and others. "The effect of L-tryptophan on daytime sleep latency in normals: correlation with blood levels." Sleep. August 1989; Vol 12, No 4: pages 345-353.

More About Melatonin

. Melatonin is disrupted by long-distance travel

At the University of Mainz in Germany researchers studied the effects of jet lag. Long distance flights, with rapid time zone shifts of more that 3 hours, disrupted the inner circadian clock. As a result, circadian rhythms were no longer synchronized by melatonin. This leads to complaints such as sleepiness, sleep disturbances and other symptoms of jet lag. Performance was found to be disturbed as well. Studies showed smaller problems with jet lag when traveling to the west. Researchers observed, "After flights to the east, resynchronization can take 5 to 14 days."

DM Rose and others. "Time zone shifts and jet lag after long-distance flights." Zeitschrift fur arztliche Fortbildung und Qualitatssicherung . October 1999; Vol 93. No 7: pages 485-490.

. Melatonin can be supplemented to reset the body's internal clock

Researchers at the University of Lucknow in India describe the role of melatonin. "Melatonin through its action on the [circadian pacemaker] synchronizes disrupted circadian rhythms and regulates a variety of daily and seasonal changes in physiology and behavior of animals. Emerging scientific evidence for the role of melatonin as therapeutic agent in the treatment circadian rhythm-associated sleep disorders including shift workers, in jet lag, in immunological functions etc, have considerably increased interest in this hormone molecule."

V Kumar. "Melatonin: a master hormone and a candidate for universal panacea." Indian Journal of Experimental Biology . May 1996; Vol 34, No 5: pages 391-402.

. The role of melatonin in sleep and jet lag

At the Institute for Clinical Pharmacology of the Freidrich-Schiller University in Germany , researchers reviewed the literature on the treatment of insomnia/sleep disturbances and concluded, "Melatonin, a naturally produced hormone and tryptophan-metabolite is thought to be involved with the sleep-wake cycle. Therefore the intake of melatonin may influence vigilance and sleep. This is particularly true for patients with jet-lag symptoms."

A Balogh. [Article in German.] Zeitschrift fur Arztliche Fortbildung und Qualitatssicherung. January 2001; Vol 95, No 1: pages 11-16.